Surgical instrument comprising a control system

ABSTRACT

A surgical instrument is disclosed. The surgical instrument comprises a first jaw, a second jaw, a staple cartridge, a firing system, an electric motor, a power source, and a control system. The first jaw is movable relative to the second jaw to capture tissue between the first jaw and the second jaw. The staple cartridge is supported by the second jaw and comprises staples removably stored therein. The firing system is configured to drive the staples toward the first jaw. The electric motor is mechanically coupled to the firing system. The power source is electrically couplable to the electric motor. The control system is electrically connected to the power source. The control system is configured to determine a first level of power supplied by the power source and apply a second level of power to the electric motor if the first level of power exceeds a predetermined threshold. The second level of power is lower than the first level of power.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application claiming priorityunder 35 U.S.C. § 120 to U.S. patent application Ser. No. 14/668,406,entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES,filed Mar. 25, 2015, now U.S. Patent Application Publication No.2015/0196347, which is a continuation application claiming priorityunder 35 U.S.C. § 120 to U.S. patent application Ser. No. 12/031,573,entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES,filed Feb. 14, 2008, the entire disclosures of which are herebyincorporated by reference herein.

The present application is related to and incorporates by reference thefollowing applications which were filed on Feb. 14, 2008:

U.S. patent application Ser. No. 12/031,542, entitled MOTORIZED SURGICALCUTTING AND FASTENING INSTRUMENT HAVING A MAGNETIC DRIVE TRAIN TORQUELIMITING DEVICE, now U.S. Pat. No. 8,459,525;

U.S. patent application Ser. No. 12/031,556, entitled MOTORIZED SURGICALCUTTING AND FASTENING INSTRUMENT, now U.S. Pat. No. 8,636,736;

U.S. patent application Ser. No. 12/031,567, entitled MOTORIZED SURGICALCUTTING AND FASTENING INSTRUMENT HAVING HANDLE BASED POWER SOURCE, nowU.S. Pat. No. 8,657,174; and

U.S. patent application Ser. No. 12/031,580, entitled MOTORIZED CUTTINGAND FASTENING INSTRUMENT HAVING CONTROL CIRCUIT FOR OPTIMIZING BATTERYUSAGE, now U.S. Pat. No. 8,622,274.

BACKGROUND

Surgical staplers have been used in the prior art to simultaneously makea longitudinal incision in tissue and apply lines of staples on opposingsides of the incision. Such instruments commonly include a pair ofcooperating jaw members that, if the instrument is intended forendoscopic or laparoscopic applications, are capable of passing througha cannula passageway. One of the jaw members receives a staple cartridgehaving at least two laterally spaced rows of staples. The other jawmember defines an anvil having staple-forming pockets aligned with therows of staples in the cartridge. Such instruments typically include aplurality of reciprocating wedges that, when driven distally, passthrough openings in the staple cartridge and engage drivers supportingthe staples to effect the firing of the staples toward the anvil.

An example of a surgical stapler suitable for endoscopic applications isdescribed in published U.S. Patent Application Publication No.2004/0232196, entitled SURGICAL STAPLING INSTRUMENT HAVING SEPARATEDISTINCT CLOSING AND FIRING SYSTEMS, now U.S. Pat. No. 7,000,818, thedisclosure of which is herein incorporated by reference. In use, aclinician is able to close the jaw members of the stapler upon tissue toposition the tissue prior to firing. Once the clinician has determinedthat the jaw members are properly gripping tissue, the clinician canfire the surgical stapler, thereby severing and stapling the tissue. Thesimultaneous severing and stapling steps avoid complications that mayarise when performing such actions sequentially with different surgicaltools that respectively only sever or staple.

In addition, it is also known in the prior art to include electrodes inthe end effector that can be used to emit/receive RF energy to form ahemostatic line along the cut line. U.S. Pat. No. 5,403,312, entitledELECTROSURGICAL HEMOSTATIC DEVICE (hereinafter the “'312 Patent”), whichis incorporated herein by reference, discloses an electrosurgicalinstrument with an end effector that compresses tissue between one pole(or electrode) of a bipolar energy source on one interfacing surface,and a second pole (or electrode) on a second interfacing surface. The RFenergy is applied through the compressed tissue in the end effector,which cauterizes the tissue. The end effector described in the '312Patent also includes staples for stapling the tissue compressed in theend effector.

Motor-powered surgical cutting and fastening instruments, where themotor powers the cutting instrument, are also known in the prior art,such as described in published U.S. Patent Application Publication No.2007/0175962, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENINGINSTRUMENT WITH TACTILE POSITION FEEDBACK, now U.S. Pat. No. 7,422,139,which is incorporated herein by reference.

SUMMARY

In one general aspect, embodiments of the present invention are directedto surgical cutting and fastening instruments. The instruments may beendoscopic instruments, such as linear endocutters or circular cutters,or laparoscopic instruments. The instruments may be comprised of staplesand/or RF electrodes for fastening tissue clamped in the end effector.

Several embodiments disclosed herein are pertinent to cordlessmotor-powered instruments. The instruments may be powered by a powerpack comprising a DC power source, such as one or more series-connectedbattery cells. A cell selection switch may control how many of thebattery cells are being used to power the motor at a given time tocontrol the power available to the motor. This allows the operator ofthe instrument to have greater control over both the speed and the powerof the motor. In another embodiment, the instrument may comprise a powerregulator, including, for example, a DC-to-DC converter, that regulatesthe voltage supplied to the motor. Further, the voltage set point forthe power regulator could be set so that the voltage delivered from thepower source is less than the voltage at which the power source deliversmaximum power. That way, the power source (e.g., a number ofseries-connected battery cells) could operate on the “left” orincreasing side of the power curve, so that increases in power would beavailable.

In addition, according to various embodiments, the power source maycomprise secondary accumulator devices, such as rechargeable batteriesor supercapacitors. Such secondary accumulator devices may be chargedrepeatably by replaceable batteries. A charge management circuit maycontrol the charging of the secondary accumulator devices and providevarious status signals, such as an alert, when the charging of thesecondary accumulator devices is complete.

In other embodiment, a power pack comprising the secondary accumulatordevices may be removable from the instrument and connectable to a remotecharger base. The charger base may charge the secondary accumulatordevices, such as from the AC electrical mains or a battery. The chargerbase may also comprise a processor and memory unit. Data stored in amemory of the removable power pack may be downloaded to the chargerbase, from which it may be uploaded for later use and analysis, such asby the user (e.g., physician), the manufacturer or distributor of theinstrument, etc. The data may comprise operating parameters, such ascharge cycle information, as well as ID values for various replaceablecomponents of the instrument, such as the staple cartridge.

In addition, the instrument may comprise a torque-limiting device tolimit the torque supplied by the motor, to limit thereby actuationforces that may damage components of the instrument. According tovarious embodiments, the torque-limiting devices may be anelectromagnetic or permanent magnet, or mechanical clutch devicesconnected (either directly or indirectly) to the output pole of themotor.

In another general aspect, the present invention is directed to RFinstruments (i.e., surgical cutting and fastening instruments withelectrodes at the end effector for applying RF energy to the tissue heldby the end effector) with new types of electrode configurations. Ingeneral, the new electrode configurations include combinations ofsmaller active electrodes and larger return electrodes. The smalleractive electrodes are used to concentrate the therapeutic energy at thetissue, while the larger return electrodes preferentially are used tocomplete the circuit with minimal impact on that tissue interface. Thereturn electrodes typically have greater mass and thereby are able tostay cooler during electrosurgical application.

In addition, the end effector, according to various embodiments, maycomprise a number of co-linear, segmented active electrodes. Thesegmented electrodes could be energized synchronously or, morepreferably, in sequence. Activating the segmented electrodes in sequenceprovides the advantages of (1) decreased instantaneous powerrequirements due to a smaller targeted area of tissue coagulation and(2) allowing other segments to fire if one is shorted out.

In addition, a number of mechanisms for activating the RF electrodes andfor articulating the end effector are disclosed herein.

In various embodiments, a surgical instrument comprising a first jaw, asecond jaw, a staple cartridge, a firing system, an electric motor, apower source, and a control system is disclosed. The first jaw ismovable relative to the second jaw to capture tissue between the firstjaw and the second jaw. The staple cartridge is supported by the secondjaw and comprises staples removably stored therein. The firing system isconfigured to drive the staples toward the first jaw. The electric motoris mechanically coupled to the firing system. The power source iselectrically couplable to the electric motor. The control system iselectrically connected to the power source. The control system isconfigured to determine a first level of power supplied by the powersource and apply a second level of power to the electric motor if thefirst level of power exceeds a predetermined threshold. The second levelof power is lower than the first level of power.

In various embodiments, a surgical instrument comprising an elongatechannel, an anvil pivotably coupled to the elongate channel, a staplecartridge positioned within the elongate channel, staples removablypositioned within the staple cartridge, a firing system configured tofire the staples toward the anvil, an electric motor mechanicallycoupled to the firing system, a power source electrically couplable tothe electric motor, and a power regulator electrically coupled to thepower source and the electric motor is disclosed. The setpoint of thepower regulator is adjustable. The surgical instrument further comprisesa control system configured to lower the setpoint of the power regulatorif a level of power supplied by the power source exceeds a predeterminedthreshold.

In various embodiments, a surgical instrument comprising a first jaw, asecond jaw pivotably connected to the first jaw, a replaceable staplecartridge removably positioned within the second jaw, staples removablypositioned within the replaceable staple cartridge, a firing systemconfigured to fire the staples toward the first jaw, an electric motormechanically coupled to the firing system, a power source electricallycouplable to the electric motor, and means for reducing a voltageapplied to the electric motor if a level of power supplied by the powersource exceeds a predetermined threshold is disclosed.

FIGURES

Various embodiments of the present invention are described herein by wayof example in conjunction with the following figures, wherein:

FIGS. 1 and 2 are perspective views of a surgical cutting and fasteninginstrument according to various embodiments of the present invention;

FIGS. 3-5 are exploded views of an end effector and shaft of theinstrument according to various embodiments of the present invention;

FIG. 6 is a side view of the end effector according to variousembodiments of the present invention;

FIG. 7 is an exploded view of the handle of the instrument according tovarious embodiments of the present invention;

FIGS. 8 and 9 are partial perspective views of the handle according tovarious embodiments of the present invention;

FIG. 10 is a side view of the handle according to various embodiments ofthe present invention;

FIG. 11 is a schematic diagram of a circuit used in the instrumentaccording to various embodiments of the present invention;

FIGS. 12-14 and 17 are schematic diagrams of circuits used to power themotor of the instrument according to various embodiments of the presentinvention;

FIG. 15 is a block diagram illustrating a charge management circuitaccording to various embodiments of the present invention;

FIG. 16 is a block diagram illustrating a charger base according tovarious embodiments of the present invention;

FIG. 18 illustrates a typical power curve of a battery;

FIGS. 19-22 illustrate embodiments of an electromagnetic, clutch-typetorque-limiting device according to various embodiments of the presentinvention;

FIGS. 23-25, 27-28, and 59 are views of the lower surface of the anvilof the instrument according to various embodiments of the presentinvention;

FIGS. 26, 53, 54, and 68 are cross-sectional front views of the endeffector according to various embodiments of the present invention;

FIGS. 29-32 show an embodiment of the end effector having RF electrodesaccording to various embodiments of the present invention;

FIGS. 33-36 show another embodiment of the end effector having RFelectrodes according to various embodiments of the present invention;

FIGS. 37-40 show another embodiment of the end effector having RFelectrodes according to various embodiments of the present invention;

FIGS. 41-44 show another embodiment of the end effector having RFelectrodes according to various embodiments of the present invention;

FIGS. 45-48 show another embodiment of the end effector having RFelectrodes according to various embodiments of the present invention;

FIGS. 49-52 show another embodiment of the end effector having RFelectrodes according to various embodiments of the present invention;

FIGS. 55 and 56 show side views of the end effector according to variousembodiments of the present invention;

FIG. 57 is a diagram of the handle of the instrument according toanother embodiment of the present invention;

FIG. 58 is a cut-away view of the handle of the embodiment of FIG. 57according to various embodiments of the present invention;

FIGS. 60-66 illustrate a multi-layer circuit board according to variousembodiments of the present invention;

FIG. 67 is a diagram illustrating an end effector according to variousembodiments of the present invention; and

FIGS. 69 and 70 are diagram of an instrument comprising a flexible neckassembly according to various embodiments of the present invention.

DESCRIPTION

FIGS. 1 and 2 depict a surgical cutting and fastening instrument 10according to various embodiments of the present invention. Theillustrated embodiment is an endoscopic instrument and, in general, theembodiments of the instrument 10 described herein are endoscopicsurgical cutting and fastening instruments. It should be noted, however,that according to other embodiments of the present invention, theinstrument may be a non-endoscopic surgical cutting and fasteninginstrument, such as a laparoscopic instrument.

The surgical instrument 10 depicted in FIGS. 1 and 2 comprises a handle6, a shaft 8, and an articulating end effector 12 pivotally connected tothe shaft 8 at an articulation pivot 14. An articulation control 16 maybe provided adjacent to the handle 6 to effect rotation of the endeffector 12 about the articulation pivot 14. In the illustratedembodiment, the end effector 12 is configured to act as an endocutterfor clamping, severing and stapling tissue, although, in otherembodiments, different types of end effectors may be used, such as endeffectors for other types of surgical devices, such as graspers,cutters, staplers, clip appliers, access devices, drug/gene therapydevices, ultrasound, RF or laser devices, etc. More details regarding RFdevices may be found in the '312 Patent.

The handle 6 of the instrument 10 may include a closure trigger 18 and afiring trigger 20 for actuating the end effector 12. It will beappreciated that instruments having end effectors directed to differentsurgical tasks may have different numbers or types of triggers or othersuitable controls for operating the end effector 12. The end effector 12is shown separated from the handle 6 by a preferably elongate shaft 8.In one embodiment, a clinician or operator of the instrument 10 mayarticulate the end effector 12 relative to the shaft 8 by utilizing thearticulation control 16, as described in more detail in published U.S.Patent Application Publication No. 2007/0158385, entitled SURGICALINSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No.7,670,334, which is incorporated herein by reference.

The end effector 12 includes in this example, among other things, astaple channel 22 and a pivotally translatable clamping member, such asan anvil 24, which are maintained at a spacing that assures effectivestapling and severing of tissue clamped in the end effector 12. Thehandle 6 includes a pistol grip 26 towards which a closure trigger 18 ispivotally drawn by the clinician to cause clamping or closing of theanvil 24 toward the staple channel 22 of the end effector 12 to therebyclamp tissue positioned between the anvil 24 and channel 22. The firingtrigger 20 is farther outboard of the closure trigger 18. Once theclosure trigger 18 is locked in the closure position as furtherdescribed below, the firing trigger 20 may rotate slightly toward thepistol grip 26 so that it can be reached by the operator using one hand.Then the operator may pivotally draw the firing trigger 20 toward thepistol grip 12 to cause the stapling and severing of clamped tissue inthe end effector 12. In other embodiments, different types of clampingmembers besides the anvil 24 could be used, such as, for example, anopposing jaw, etc.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping the handle 6 of aninstrument 10. Thus, the end effector 12 is distal with respect to themore proximal handle 6. It will be further appreciated that, forconvenience and clarity, spatial terms such as “vertical” and“horizontal” are used herein with respect to the drawings. However,surgical instruments are used in many orientations and positions, andthese terms are not intended to be limiting and absolute.

The closure trigger 18 may be actuated first. Once the clinician issatisfied with the positioning of the end effector 12, the clinician maydraw back the closure trigger 18 to its fully closed, locked positionproximate to the pistol grip 26. The firing trigger 20 may then beactuated. The firing trigger 20 returns to the open position (shown inFIGS. 1 and 2) when the clinician removes pressure, as described morefully below. A release button on the handle 6, when depressed mayrelease the locked closure trigger 18. The release button may beimplemented in various forms such as, for example, as a slide releasebutton 160 shown in FIG. 7 or any of the mechanisms described inpublished U.S. Patent Application Publication No. 2007/0175955, which isincorporated herein by reference.

FIG. 3 is an exploded view of the end effector 12 according to variousembodiments. As shown in the illustrated embodiment, the end effector 12may include, in addition to the previously mentioned channel 22 andanvil 24, a cutting instrument 32, a sled 33, a staple cartridge 34 thatis removably seated in the channel 22, and a helical screw shaft 36. Thecutting instrument 32 may be, for example, a knife. The anvil 24 may bepivotably opened and closed at a pivot point 25 connected to theproximate end of the channel 22. The anvil 24 may also include a tab 27at its proximate end that is inserted into a component of the mechanicalclosure system (described further below) to open and close the anvil 24.When the closure trigger 18 is actuated, that is, drawn in by a user ofthe instrument 10, the anvil 24 may pivot about the pivot point 25 intothe clamped or closed position. If clamping of the end effector 12 issatisfactory, the operator may actuate the firing trigger 20, which, asexplained in more detail below, causes the knife 32 and sled 33 totravel longitudinally along the channel 22, thereby cutting tissueclamped within the end effector 12. The movement of the sled 33 alongthe channel 22 causes the staples of the staple cartridge 34 to bedriven through the severed tissue and against the closed anvil 24, whichturns the staples to fasten the severed tissue. In various embodiments,the sled 33 may be an integral component of the cartridge 34. U.S. Pat.No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING ANE-BEAM FIRING MECHANISM, which is incorporated herein by reference,provides more details about such two-stroke cutting and fasteninginstruments. The sled 33 may be part of the cartridge 34, such that whenthe knife 32 retracts following the cutting operation, the sled 33 doesnot retract.

It should be noted that although the embodiments of the instrument 10described herein employ an end effector 12 that staples the severedtissue, in other embodiments different techniques for fastening orsealing the severed tissue may be used. For example, end effectors thatuse RF energy or adhesives to fasten the severed tissue may also beused. U.S. Pat. No. 5,709,680 entitled ELECTROSURGICAL HEMOSTATICDEVICE, and U.S. Pat. No. 5,688,270 entitled ELECTROSURGICAL HEMOSTATICDEVICE WITH RECESSED AND/OR OFFSET ELECTRODES, which are incorporatedherein by reference, disclose an endoscopic cutting instrument that usesRF energy to seal the severed tissue. Published U.S. Patent ApplicationPublication No. 2007/0102453, now U.S. Pat. No. 7,673,783 and publishedU.S. Patent Application Publication No. 2007/0102452, now U.S. Pat. No.7,607,557, which are also incorporated herein by reference, discloseendoscopic cutting instruments that use adhesives to fasten the severedtissue. Accordingly, although the description herein refers tocutting/stapling operations and the like below, it should be recognizedthat this is an exemplary embodiment and is not meant to be limiting.Other tissue-fastening techniques may also be used.

FIGS. 4 and 5 are exploded views and FIG. 6 is a side view of the endeffector 12 and shaft 8 according to various embodiments. As shown inthe illustrated embodiment, the shaft 8 may include a proximate closuretube 40 and a distal closure tube 42 pivotably linked by a pivot links44. The distal closure tube 42 includes an opening 45 into which the tab27 on the anvil 24 is inserted in order to open and close the anvil 24,as further described below. Disposed inside the closure tubes 40, 42 maybe a proximate spine tube 46. Disposed inside the proximate spine tube46 may be a main rotational (or proximate) drive shaft 48 thatcommunicates with a secondary (or distal) drive shaft 50 via a bevelgear assembly 52. The secondary drive shaft 50 is connected to a drivegear 54 that engages a proximate drive gear 56 of the helical screwshaft 36. The vertical bevel gear 52 b may sit and pivot in an opening57 in the distal end of the proximate spine tube 46. A distal spine tube58 may be used to enclose the secondary drive shaft 50 and the drivegears 54, 56. Collectively, the main drive shaft 48, the secondary driveshaft 50, and the articulation assembly (e.g., the bevel gear assembly52 a-c) are sometimes referred to herein as the “main drive shaftassembly.”

A bearing 38, positioned at a distal end of the staple channel 22,receives the helical drive screw 36, allowing the helical drive screw 36to freely rotate with respect to the channel 22. The helical screw shaft36 may interface a threaded opening (not shown) of the knife 32 suchthat rotation of the shaft 36 causes the knife 32 to translate distallyor proximately (depending on the direction of the rotation) through thestaple channel 22. Accordingly, when the main drive shaft 48 is causedto rotate by actuation of the firing trigger 20 (as explained in moredetail below), the bevel gear assembly 52 a-c causes the secondary driveshaft 50 to rotate, which in turn, because of the engagement of thedrive gears 54, 56, causes the helical screw shaft 36 to rotate, whichcauses the knife driving member 32 to travel longitudinally along thechannel 22 to cut any tissue clamped within the end effector. The sled33 may be made of, for example, plastic, and may have a sloped distalsurface. As the sled 33 traverses the channel 22, the sloped forwardsurface may push up or drive the staples in the staple cartridge throughthe clamped tissue and against the anvil 24. The anvil 24 turns thestaples, thereby stapling the severed tissue. When the knife 32 isretracted, the knife 32 and sled 33 may become disengaged, therebyleaving the sled 33 at the distal end of the channel 22.

FIGS. 7-10 illustrate an exemplary embodiment of a motor-drivenendocutter. The illustrated embodiment provides user-feedback regardingthe deployment and loading force of the cutting instrument in the endeffector. In addition, the embodiment may use power provided by the userin retracting the firing trigger 20 to power the device (a so-called“power assist” mode). As shown in the illustrated embodiment, the handle6 includes exterior lower side pieces 59, 60 and exterior upper sidepieces 61, 62 that fit together to form, in general, the exterior of thehandle 6. A battery 64, such as a Li ion battery, may be provided in thepistol grip portion 26 of the handle 6. The battery 64 powers a motor 65disposed in an upper portion of the pistol grip portion 26 of the handle6. According to various embodiments, a number of battery cells connectedin series may be used to power the motor 65.

The motor 65 may be a DC brushed driving motor having a maximum rotationof approximately 25,000 RPM with no load. The motor 64 may drive a 90°bevel gear assembly 66 comprising a first bevel gear 68 and a secondbevel gear 70. The bevel gear assembly 66 may drive a planetary gearassembly 72. The planetary gear assembly 72 may include a pinion gear 74connected to a drive shaft 76. The pinion gear 74 may drive a matingring gear 78 that drives a helical gear drum 80 via a drive shaft 82. Aring 84 may be threaded on the helical gear drum 80. Thus, when themotor 65 rotates, the ring 84 is caused to travel along the helical geardrum 80 by means of the interposed bevel gear assembly 66, planetarygear assembly 72, and ring gear 78.

The handle 6 may also include a run motor sensor 110 in communicationwith the firing trigger 20 to detect when the firing trigger 20 has beendrawn in (or “closed”) toward the pistol grip portion 26 of the handle 6by the operator to thereby actuate the cutting/stapling operation by theend effector 12. The sensor 110 may be a proportional sensor such as,for example, a rheostat, or variable resistor. When the firing trigger20 is drawn in, the sensor 110 detects the movement, and sends anelectrical signal indicative of the voltage (or power) to be supplied tothe motor 65. When the sensor 110 is a variable resistor or the like,the rotation of the motor 65 may be generally proportional to the amountof movement of the firing trigger 20. That is, if the operator onlydraws or closes the firing trigger 20 in a little bit, the rotation ofthe motor 65 is relatively low. When the firing trigger 20 is fullydrawn in (or in the fully closed position), the rotation of the motor 65is at its maximum. In other words, the harder the user pulls on thefiring trigger 20, the more voltage is applied to the motor 65, causinggreater rates of rotation.

The handle 6 may include a middle handle piece 104 adjacent to the upperportion of the firing trigger 20. The handle 6 also may comprise a biasspring 112 connected between posts on the middle handle piece 104 andthe firing trigger 20. The bias spring 112 may bias the firing trigger20 to its fully open position. In that way, when the operator releasesthe firing trigger 20, the bias spring 112 will pull the firing trigger20 to its open position, thereby removing actuation of the sensor 110,thereby stopping rotation of the motor 65. Moreover, by virtue of thebias spring 112, any time a user closes the firing trigger 20, the userwill experience resistance to the closing operation, thereby providingthe user with feedback as to the amount of rotation exerted by the motor65. Further, the operator could stop retracting the firing trigger 20 tothereby remove force from the sensor 100, to thereby stop the motor 65.As such, the user may stop the deployment of the end effector 12,thereby providing a measure of control of the cutting/fasteningoperation to the operator.

The distal end of the helical gear drum 80 includes a distal drive shaft120 that drives a ring gear 122, which mates with a pinion gear 124. Thepinion gear 124 is connected to the main drive shaft 48 of the maindrive shaft assembly. In that way, rotation of the motor 65 causes themain drive shaft assembly to rotate, which causes actuation of the endeffector 12, as described above.

The ring 84 threaded on the helical gear drum 80 may include a post 86that is disposed within a slot 88 of a slotted arm 90. The slotted arm90 has an opening 92 at its opposite end 94 that receives a pivot pin 96that is connected between the handle exterior side pieces 59, 60. Thepivot pin 96 is also disposed through an opening 100 in the firingtrigger 20 and an opening 102 in the middle handle piece 104.

In addition, the handle 6 may include a reverse motor (or end-of-strokesensor) 130 and a stop motor (or beginning-of-stroke) sensor 142. Invarious embodiments, the reverse motor sensor 130 may be a limit switchlocated at the distal end of the helical gear drum 80 such that the ring84 threaded on the helical gear drum 80 contacts and trips the reversemotor sensor 130 when the ring 84 reaches the distal end of the helicalgear drum 80. The reverse motor sensor 130, when activated, sends asignal to the motor 65 to reverse its rotation direction, therebywithdrawing the knife 32 of the end effector 12 following the cuttingoperation. The stop motor sensor 142 may be, for example, anormally-closed limit switch. In various embodiments, it may be locatedat the proximate end of the helical gear drum 80 so that the ring 84trips the switch 142 when the ring 84 reaches the proximate end of thehelical gear drum 80.

In operation, when an operator of the instrument 10 pulls back thefiring trigger 20, the sensor 110 detects the deployment of the firingtrigger 20 and sends a signal to the motor 65 to cause forward rotationof the motor 65 at, for example, a rate proportional to how hard theoperator pulls back the firing trigger 20. The forward rotation of themotor 65 in turn causes the ring gear 78 at the distal end of theplanetary gear assembly 72 to rotate, thereby causing the helical geardrum 80 to rotate, causing the ring 84 threaded on the helical gear drum80 to travel distally along the helical gear drum 80. The rotation ofthe helical gear drum 80 also drives the main drive shaft assembly asdescribed above, which in turn causes deployment of the knife 32 in theend effector 12. That is, the knife 32 and sled 33 are caused totraverse the channel 22 longitudinally, thereby cutting tissue clampedin the end effector 12. Also, the stapling operation of the end effector12 is caused to happen in embodiments where a stapling-type end effectoris used.

By the time the cutting/stapling operation of the end effector 12 iscomplete, the ring 84 on the helical gear drum 80 will have reached thedistal end of the helical gear drum 80, thereby causing the reversemotor sensor 130 to be tripped, which sends a signal to the motor 65 tocause the motor 65 to reverse its rotation. This in turn causes theknife 32 to retract, and also causes the ring 84 on the helical geardrum 80 to move back to the proximate end of the helical gear drum 80.

The middle handle piece 104 includes a backside shoulder 106 thatengages the slotted arm 90 as best shown in FIGS. 8 and 9. The middlehandle piece 104 also has a forward motion stop 107 that engages thefiring trigger 20. The movement of the slotted arm 90 is controlled, asexplained above, by rotation of the motor 65. When the slotted arm 90rotates CCW as the ring 84 travels from the proximate end of the helicalgear drum 80 to the distal end, the middle handle piece 104 will be freeto rotate CCW. Thus, as the user draws in the firing trigger 20, thefiring trigger 20 will engage the forward motion stop 107 of the middlehandle piece 104, causing the middle handle piece 104 to rotate CCW. Dueto the backside shoulder 106 engaging the slotted arm 90, however, themiddle handle piece 104 will only be able to rotate CCW as far as theslotted arm 90 permits. In that way, if the motor 65 should stoprotating for some reason, the slotted arm 90 will stop rotating, and theuser will not be able to further draw in the firing trigger 20 becausethe middle handle piece 104 will not be free to rotate CCW due to theslotted arm 90.

Components of an exemplary closure system for closing (or clamping) theanvil 24 of the end effector 12 by retracting the closure trigger 18 arealso shown in FIGS. 7-10. In the illustrated embodiment, the closuresystem includes a yoke 250 connected to the closure trigger 18 by a pin251 that is inserted through aligned openings in both the closuretrigger 18 and the yoke 250. A pivot pin 252, about which the closuretrigger 18 pivots, is inserted through another opening in the closuretrigger 18 which is offset from where the pin 251 is inserted throughthe closure trigger 18. Thus, retraction of the closure trigger 18causes the upper part of the closure trigger 18, to which the yoke 250is attached via the pin 251, to rotate CCW. The distal end of the yoke250 is connected, via a pin 254, to a first closure bracket 256. Thefirst closure bracket 256 connects to a second closure bracket 258.Collectively, the closure brackets 256, 258 define an opening in whichthe proximate end of the proximate closure tube 40 (see FIG. 4) isseated and held such that longitudinal movement of the closure brackets256, 258 causes longitudinal motion by the proximate closure tube 40.The instrument 10 also includes a closure rod 260 disposed inside theproximate closure tube 40. The closure rod 260 may include a window 261into which a post 263 on one of the handle exterior pieces, such asexterior lower side piece 59 in the illustrated embodiment, is disposedto fixedly connect the closure rod 260 to the handle 6. In that way, theproximate closure tube 40 is capable of moving longitudinally relativeto the closure rod 260. The closure rod 260 may also include a distalcollar 267 that fits into a cavity 269 in proximate spine tube 46 and isretained therein by a cap 271 (see FIG. 4).

In operation, when the yoke 250 rotates due to retraction of the closuretrigger 18, the closure brackets 256, 258 cause the proximate closuretube 40 to move distally (i.e., away from the handle end of theinstrument 10), which causes the distal closure tube 42 to movedistally, which causes the anvil 24 to rotate about the pivot point 25into the clamped or closed position. When the closure trigger 18 isunlocked from the locked position, the proximate closure tube 40 iscaused to slide proximately, which causes the distal closure tube 42 toslide proximately, which, by virtue of the tab 27 being inserted in thewindow 45 of the distal closure tube 42, causes the anvil 24 to pivotabout the pivot point 25 into the open or unclamped position. In thatway, by retracting and locking the closure trigger 18, an operator mayclamp tissue between the anvil 24 and channel 22, and may unclamp thetissue following the cutting/stapling operation by unlocking the closuretrigger 20 from the locked position.

FIG. 11 is a schematic diagram of an electrical circuit of theinstrument 10 according to various embodiments of the present invention.When an operator initially pulls in the firing trigger 20 after lockingthe closure trigger 18, the sensor 110 is activated, allowing current toflow there through. If the normally-open reverse motor sensor switch 130is open (meaning the end of the end effector stroke has not beenreached), current will flow to a single pole, double throw relay 132.Since the reverse motor sensor switch 130 is not closed, the inductor134 of the relay 132 will not be energized, so the relay 132 will be inits non-energized state. The circuit also includes a cartridge lockoutsensor 136. If the end effector 12 includes a staple cartridge 34, thesensor 136 will be in the closed state, allowing current to flow.Otherwise, if the end effector 12 does not include a staple cartridge34, the sensor 136 will be open, thereby preventing the battery 64 frompowering the motor 65.

When the staple cartridge 34 is present, the sensor 136 is closed, whichenergizes a single pole, single throw relay 138. When the relay 138 isenergized, current flows through the relay 136, through the variableresistor sensor 110, and to the motor 65 via a double pole, double throwrelay 140, thereby powering the motor 65, and allowing it to rotate inthe forward direction. When the end effector 12 reaches the end of itsstroke, the reverse motor sensor 130 will be activated, thereby closingthe switch 130 and energizing the relay 134. This causes the relay 134to assume its energized state (not shown in FIG. 13), which causescurrent to bypass the cartridge lockout sensor 136 and variable resistor110, and instead causes current to flow to both the normally-closeddouble pole, double throw relay 142 and back to the motor 65, but in amanner, via the relay 140, that causes the motor 65 to reverse itsrotational direction. Because the stop motor sensor switch 142 isnormally closed, current will flow back to the relay 134 to keep itclosed until the switch 142 opens. When the knife 32 is fully retracted,the stop motor sensor switch 142 is activated, causing the switch 142 toopen, thereby removing power from the motor 65.

In other embodiments, rather than a proportional-type sensor 110, anon-off type sensor could be used. In such embodiments, the rate ofrotation of the motor 65 would not be proportional to the force appliedby the operator. Rather, the motor 65 would generally rotate at aconstant rate. But the operator would still experience force feedbackbecause the firing trigger 20 is geared into the gear drive train.

Additional configurations for motorized surgical instruments aredisclosed in published U.S. Patent Application Publication No.2007/0175962, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENINGINSTRUMENT WITH TACTILE POSITION FEEDBACK, now U.S. Pat. No. 7,422,139,which is incorporated herein by reference.

In a motorized surgical instrument, such as one of the motorizedendoscopic instruments described above or in a motorized circular cutterinstrument, the motor may be powered by a number of battery cellsconnected in series. Further, it may be desirable in certaincircumstances to power the motor with some fraction of the total numberof battery cells. For example, as shown in FIG. 12, the motor 65 may bepowered by a power pack 299 comprising six (6) battery cells 310connected in series. The battery cells 310 may be, for example, 3-voltlithium battery cells, such as CR 123A battery cells, although in otherembodiments, different types of battery cells could be used (includingbattery cells with different voltage levels and/or differentchemistries). If six 3-volt battery cells 310 were connected in seriesto power the motor 65, the total voltage available to power the motor 65would be 18 volts. The battery cells 310 may comprise rechargeable ornon-rechargeable battery cells.

In such an embodiment, under the heaviest loads, the input voltage tothe motor 65 may sag to about nine to ten volts. At this operatingcondition, the power pack 299 is delivering maximum power to the motor65. Accordingly, as shown in FIG. 12, the circuit may include a switch312 that selectively allows the motor 65 to be powered by either (1) allof the battery cells 310 or (2) a fraction of the battery cells 310. Asshown in FIG. 12, by proper selection, the switch 312 may allow themotor 65 to be powered by all six battery cells or four of the batterycells. That way, the switch 312 could be used to power the motor 65 witheither 18 volts (when using all six battery cells 310) or 12 volts (suchusing four of the second battery cells). In various embodiments, thedesign choice for the number of battery cells in the fraction that isused to power the motor 65 may be based on the voltage required by themotor 65 when operating at maximum output for the heaviest loads.

The switch 312 may be, for example, an electromechanical switch, such asa micro switch. In other embodiments, the switch 312 may be implementedwith a solid-state switch, such as transistor. A second switch 314, suchas a push button switch, may be used to control whether power is appliedto the motor 65 at all. Also, a forward/reverse switch 316 may be usedto control whether the motor 65 rotates in the forward direction or thereverse direction. The forward/reverse switch 316 may be implementedwith a double pole-double throw switch, such as the relay 140 shown inFIG. 11.

In operation, the user of the instrument 10 could select the desiredpower level by using some sort of switch control, such as aposition-dependent switch (not shown), such as a toggle switch, amechanical lever switch, or a cam, which controls the position of theswitch 312. Then the user may activate the second switch 314 to connectthe selected battery cells 310 to the motor 65. In addition, the circuitshown in FIG. 12 could be used to power the motor of other types ofmotorized surgical instruments, such as circular cutters and/orlaparoscopic instruments. More details regarding circular cutters may befound in published U.S. Patent Application Publication Nos.2006/0047307, now U.S. Pat. No. 8,317,074, and 2007/0262116, now U.S.Pat. No. 7,500,979, which are incorporated herein by reference.

In other embodiments, as shown in FIG. 13, a primary power source 340,such as a battery cell, such as a CR2 or CR123A battery cell, may beused to charge a number of secondary accumulator devices 342. Theprimary power source 340 may comprise one or a number ofseries-connected battery cells, which are preferably replaceable in theillustrated embodiment. The secondary accumulator devices 342 maycomprise, for example, rechargeable battery cells and/or supercapacitors(also known as “ultracapacitors” or “electrochemical double layercapacitors” (EDLC)). Supercapacitors are electrochemical capacitors thathave an unusually high energy density when compared to commonelectrolytic capacitors, typically on the order of thousands of timesgreater than a high-capacity electrolytic capacitor.

The primary power source 340 may charge the secondary accumulatordevices 342. Once sufficiently charged, the primary power source 340 maybe removed and the secondary accumulator devices 342 may be used topower the motor 65 during a procedure or operation. The accumulatingdevices 342 may take about fifteen to thirty minutes to charge invarious circumstances. Supercapacitors have the characteristic they cancharge and discharge extremely rapidly in comparison to conventionalbatteries. In addition, whereas batteries are good for only a limitednumber of charge/discharge cycles, supercapacitors can often becharged/discharged repeatedly, sometimes for tens of millions of cycles.For embodiments using supercapacitors as the secondary accumulatordevices 342, the supercapacitors may comprise carbon nanotubes,conductive polymers (e.g., polyacenes), or carbon aerogels.

As shown in FIG. 14, a charge management circuit 344 could be employedto determine when the secondary accumulator devices 342 are sufficientlycharged. The charge management circuit 344 may include an indicator,such as one or more LEDs, an LCD display, etc., that is activated toalert a user of the instrument 10 when the secondary accumulator devices342 are sufficiently charged.

The primary power source 340, the secondary accumulator devices 342, andthe charge management circuit 344 may be part of a power pack in thepistol grip portion 26 of the handle 6 of the instrument 10, or inanother part of the instrument 10. The power pack may be removable fromthe pistol grip portion 26, in which case, when the instrument 10 is tobe used for surgery, the power pack may be inserted aseptically into thepistol grip portion 26 (or other position in the instrument according toother embodiments) by, for example, a circulating nurse assisting in thesurgery. After insertion of the power pack, the nurse could put thereplaceable primary power source 340 in the power pack to charge up thesecondary accumulator devices 342 a certain time period prior to use ofthe instrument 10, such as thirty minutes. When the secondaryaccumulator devices 342 are charged, the charge management circuit 344may indicate that the power pack is ready for use. At this point, thereplaceable primary power source 340 may be removed. During theoperation, the user of the instrument 10 may then activate the motor 65,such as by activating the switch 314, whereby the secondary accumulatordevices 342 power the motor 65. Thus, instead of having a number ofdisposable batteries to power the motor 65, one disposable battery (asthe primary power source 340) could be used in such an embodiment, andthe secondary accumulator devices 342 could be reusable. In alternativeembodiments, however, it should be noted that the secondary accumulatordevices 342 could be non-rechargeable and/or non-reusable. The secondaryaccumulators 342 may be used with the cell selection switch 312described above in connection with FIG. 12.

The charge management circuit 344 may also include indicators (e.g.,LEDs or LCD display) that indicate how much charge remains in thesecondary accumulator devices 342. That way, the surgeon (or other userof the instrument 10) can see how much charge remains through the courseof the procedure involving the instrument 10.

The charge management circuit 344, as shown in FIG. 15, may comprise acharge meter 345 for measuring the charge across the secondaryaccumulators 342. The charge management circuit 344 also may comprise anon-volatile memory 346, such as flash or ROM memory, and one or moreprocessors 348. The processor(s) 348 may be connected to the memory 346to control the memory. In addition, the processor(s) 348 may beconnected to the charge meter 345 to read the readings of and otherwisecontrol the charge meter 345. Additionally, the processor(s) 348 maycontrol the LEDs or other output devices of the charge managementcircuit 344. The processor(s) 348 can store parameters of the instrument10 in the memory 346. The parameters may include operating parameters ofthe instrument that are sensed by various sensors that may be installedor employed in the instrument 10, such as, for example, the number offirings, the levels of forces involved, the distance of the compressiongap between the opposing jaws of the end effector 12, the amount ofarticulation, etc. Additionally, the parameters stored in the memory 346may comprise ID values for various components of the instrument 10 thatthe charge management circuit 344 may read and store. The componentshaving such IDs may be replaceable components, such as the staplecartridge 34. The IDs may be for example, RFIDs that the chargemanagement circuit 344 reads via a RFID transponder 350. The RFIDtransponder 350 may read RFIDs from components of the instrument, suchas the staple cartridge 34, that include RFID tags. The ID values may beread, stored in the memory 346, and compared by the processor 348 to alist of acceptable ID values stored in the memory 346 or another storeassociated with the charge management circuit, to determine, forexample, if the removable/replaceable component associated with the readID value is authentic and/or proper. According to various embodiments,if the processor 348 determines that the removable/replaceable componentassociated with the read ID value is not authentic, the chargemanagement circuit 344 may prevent use of the power pack by theinstrument 10, such as by opening a switch (not shown) that wouldprevent power from the power pack being delivered to the motor 65.According to various embodiments, various parameters that the processor348 may evaluate to determine whether the component is authentic and/orproper include: date code; component model/type; manufacturer; regionalinformation; and previous error codes.

The charge management circuit 344 may also comprise an i/o interface 352for communicating with another device, such as described below. Thatway, the parameters stored in the memory 346 may be downloaded toanother device. The i/o interface 352 may be, for example, a wired orwireless interface.

As mentioned before, the power pack may comprise the secondaryaccumulators 342, the charge management circuit 344, and/or the f/rswitch 316. According to various embodiments, as shown in FIG. 16, thepower pack 299 could be connected to a charger base 362, which may,among other things, charge the secondary accumulators 342 in the powerpack. The charger base 362 could be connected to the power pack 299 byconnecting aseptically the charger base 362 to the power pack 299 whilethe power pack is installed in the instrument 10. In other embodimentswhere the power pack is removable, the charger base 362 could beconnected to the power pack 299 by removing the power pack 299 from theinstrument 10 and connecting it to the charger base 362. For suchembodiments, after the charger base 362 sufficiently charges thesecondary accumulators 342, the power pack 299 may be asepticallyinstalled in the instrument 10.

As shown in FIG. 16, the charger base 362 may comprise a power source364 for charging the secondary accumulators 342. The power source 364 ofthe charger base 362 may be, for example, a battery (or a number ofseries-connected batteries), or an AC/DC converter that converters ACpower, such as from electrical power mains, to DC, or any other suitablepower source for charging the secondary accumulators 342. The chargerbase 362 may also comprise indicator devices, such as LEDs, a LCDdisplay, etc., to show the charge status of the secondary accumulators342.

In addition, as shown in FIG. 16, the charger base 362 may comprise oneor more processors 366, one or more memory units 368, and i/o interfaces370, 372. Through the first i/o interface 370, the charger base 362 maycommunicate with the power pack 299 (via the power pack's i/o interface352). That way, for example, data stored in the memory 346 of the powerpack 299 may be downloaded to the memory 368 of the charger base 362. Inthat way, the processor 366 can evaluate the ID values for theremovable/replaceable components, downloaded from the charge managementcircuit 344, to determine the authenticity and suitability of thecomponents. The operating parameters downloaded from the chargemanagement circuit 344 may also stored in the memory 368, and then maythen be downloaded to another computer device via the second i/ointerface 372 for evaluation and analysis, such as by the hospitalsystem in which the operation involving the instrument 10 is performed,by the office of the surgeon, by the distributor of the instrument, bythe manufacturer of the instrument, etc.

The charger base 362 may also comprise a charge meter 374 for measuringthe charge across the secondary accumulators 342. The charge meter 374may be in communication with the processor(s) 366, so that theprocessor(s) 366 can determine in real-time the suitability of the powerpack 299 for use to ensure high performance.

In another embodiment, as shown in FIG. 17, the battery circuit maycomprise a power regulator 320 to control the power supplied by thepower savers 310 to the motor 65. The power regulator 320 may also bepart of the power pack 299, or it may be a separate component. Asmentioned above, the motor 65 may be a brushed DC motor. The speed ofbrushed DC motors generally is proportional to the applied inputvoltage. The power regulator 320 may provide a highly regulated outputvoltage to the motor 65 so that the motor 65 will operate at a constant(or substantially constant) speed. According to various embodiments, thepower regulator 320 may comprise a switch-mode power converter, such asa buck-boost converter, as shown in the example of FIG. 17. Such abuck-boost converter 320 may comprise a power switch 322, such as a FET,a rectifier 324, an inductor 326, and a capacitor 328. When the powerswitch 322 is on, the input voltage source (e.g., the power sources 310)is directly connected to the inductor 326, which stores energy in thisstate. In this state, the capacitor 328 supplies energy to the outputload (e.g., the motor 65). When the power switch 320 is in the offstate, the inductor 326 is connected to the output load (e.g., the motor65) and the capacitor 328, so energy is transferred from the inductor326 to the capacitor 328 and the load 65. A control circuit 330 maycontrol the power switch 322. The control circuit 330 may employ digitaland/or analog control loops. In addition, in other embodiments, thecontrol circuit 330 may receive control information from a mastercontroller (not shown) via a communication link, such as a serial orparallel digital data bus. The voltage set point for the output of thepower regulator 320 may be set, for example, to one-half of the opencircuit voltage, at which point the maximum power available from thesource is available.

In other embodiments, different power converter topologies may beemployed, including linear or switch-mode power converters. Otherswitch-mode topologies that may be employed include a flyback, forward,buck, boost, and SEPIC. The set point voltage for the power regulator320 could be changed depending on how many of the battery cells arebeing used to power the motor 65. Additionally, the power regulator 320could be used with the secondary accumulator devices 342 shown in FIG.13. Further, the forward-reverse switch 316 could be incorporated intothe power regulator 320, although it is shown separately in FIG. 17.

Batteries can typically be modeled as an ideal voltage source and asource resistance. For an ideal model, when the source and loadresistance are matched, maximum power is transferred to the load. FIG.18 shows a typical power curve for a battery. When the battery circuitis open, the voltage across the battery is high (at its open circuitvalue) and the current drawn from the battery is zero. The powerdelivered from the battery is zero also. As more current is drawn fromthe battery, the voltage across the battery decreases. The powerdelivered by the battery is the product of the current and the voltage.The power reaches its peak around at a voltage level that is less thanthe open circuit voltage. As shown in FIG. 18, with most batterychemistries there is a sharp drop in the voltage/power at higher currentbecause of the chemistry or positive temperature coefficient (PTC), orbecause of a battery protection device.

Particularly for embodiments using a battery (or batteries) to power themotor 65 during a procedure, the control circuit 330 can monitor theoutput voltage and control the set point of the regulator 320 so thatthe battery operates on the “left” or power-increasing side of the powercurve. If the battery reaches the peak power level, the control circuit330 can change (e.g., lower) the set point of the regulator so that lesstotal power is being demanded from the battery. The motor 65 would thenslow down. In this way, the demand from the power pack would rarely ifever exceed the peak available power so that a power-starving situationduring a procedure could be avoided.

In addition, according to other embodiments, the power drawn from thebattery may be optimized in such a way that the chemical reactionswithin the battery cells would have time to recover, to thereby optimizethe current and power available from the battery. In pulsed loads,batteries typically provide more power at the beginning of the pulsethat toward the end of the pulse. This is due to several factors,including: (1) the PTC may be changing its resistance during the pulse;(2) the temperature of the battery may be changing; and (3) theelectrochemical reaction rate is changing due to electrolyte at thecathode being depleted and the rate of diffusion of the freshelectrolyte limits the reaction rate. According to various embodiments,the control circuit 330 may control the converter 320 so that it draws alower current from the battery to allow the battery to recover before itis pulsed again.

According to other embodiments, the instrument 10 may comprise aclutch-type torque-limiting device. The clutch-type torque-limitingdevice may be located, for example, between the motor 65 and the bevelgear 68, between the bevel gear 70 and the planetary gear assembly 72,or on the output shaft of the planetary gear assembly 72. According tovarious embodiments, the torque-limiting device may use anelectromagnetic or permanent magnetic clutch.

FIGS. 19 to 22 show a sample electromagnetic clutch 400 that could beused in the instrument 10 according to various embodiments. The clutch400 may comprise a horseshoe-shaped stator 402 having magnetic disks404, 406 at each end. The first disk 404 may be connected to an axiallymovable, rotatable pole piece 408, such as the output pole of the motor65. The second magnetic disk 406 may be connected to an axiallystationary, rotatable pole piece 410, such as an input pole to a gearbox of the instrument 10. In the views of FIGS. 19 and 20, the firstpole piece 408 is axially pulled away from the second pole piece 410 bya clearance 412 such that the magnetic disks 404, 406 are not engaged. Awire coil (not shown), which may be wrapped around the stator 402 may beused to create the electromagnetic flux needed to actuate the clutch400. When the coil conducts an electrical current, the resultingmagnetic flux may cause the two magnetic disks 404, 406 to attract,causing the first pole piece 408 to move axially toward the second polepiece 410, thereby causing the two magnetic disks 404, 406 to becomeengaged, as shown in FIGS. 21 and 22, such that the two pole pieces 408,410 will rotate together until the torque exceeds the friction torquegenerated between the faces of magnetic disks 404 and 406.

The attractive force between the two disks 404, 406 and thecorresponding torque capacity of the clutch 400 could be controlled bycontrolling the diameter of the disks 404, 406, the coefficient offriction between the contacting faces of magnetic disks 404 and 406, andby using magnetic materials for the disks 404, 406 that saturate at aknown and controllable flux density. Therefore, even if there was anoperating condition where more current was passed through the coil, themagnetic material of the disks 404, 406 would not generate a greaterattractive force and subsequent limiting torque.

Utilization of such a clutch has many additional potential benefits.Being electrically controlled, the clutch 400 could be quicklydeactivated by removing current from the wire to limit the amount ofheat generated within the clutch 400 and within the motor 65. Bydisconnecting the motor from the rest of the drive train, via the clutch400, most of the stored inertial energy in the drive train would bedisconnected, limiting shock if the output were to be blocked suddenly.In addition, by being electrically controlled, some limited slippingcould be designed-in to aid in reducing shocks when restarting the drivetrain under load. Further, because the magnetic saturation properties ofone or more of the components (e.g., the magnetic disks 404, 406) withinthe clutch could be used to control the torque limit instead of coilcurrent, the clutch 400 would be less sensitive to changes in systemvoltage. The torque limit in such embodiments would be primarily afunction of the physical dimensions of the components of the clutch(e.g., the magnetic disks 404, 406) and would not require voltageregulators or other external components for proper operation.

In another embodiment, rather than using an electromagnetic clutch, thetorque-limiting device may comprise a permanent magnet (not shown). Thepermanent magnet may be connected, for example, to the first,axially-movable, pole piece 408, and attract the axially-fixed secondpole piece 410, or vice versa. In such embodiments, one of the disks404, 406 could be made of a permanent magnet and the other one of amagnetic material like iron. In a slight variation, the stator 402 couldbe made in the form of a permanent magnet, causing the magnetic disks404 and 406 to be attracted to each other. Because of the permanentmagnet, the two disks 404, 406 would be engaged always. Using apermanent magnet would not provide as accurate as torque control as theelectromagnetic clutch configuration described above, but it would havethe advantages of: (1) not requiring controls or control logic tocontrol the current through the coil; (2) being more compact that theelectromagnetic clutch configuration; and (3) simplifying design of theinstrument 10.

As mentioned previously, the end effector 12 may emit RF energy tocoagulate tissue clamped in the end effector. The RF energy may betransmitted between electrodes in the end effector 12. A RF source (notshown), comprising, for example, an oscillator and an amplifier, amongother components, which may supply the RF energy to the electrode, maybe located in the instrument itself, such as in the handle 6 for acordless instrument 10, or the RF source may be external to theinstrument 10. The RF source may be activated as described furtherbelow.

According to various embodiments, the end effector 12 may comprisemultiple sections (or segments) of electrodes. For example, as shown inthe example of FIG. 23, the lower surface of the anvil 24 (i.e., thesurface facing the staple cartridge 34) may comprise three co-linear RFsegments. In this example, each segment has the same length (e.g., 20mm), although in other embodiments there may be more or fewer segments,and the segments may have different lengths. In the example of FIG. 23,there are three pairs of active or “anode” terminals or electrodes 500lined up longitudinally along each side of the channel length on thelower surface of the anvil 24. In particular, in the illustratedembodiment there is a pair of distal electrodes 500 ₁, a pair of middleelectrodes 500 ₂, and a pair of proximate electrodes 500 ₃ on each sideof the knife channel 516. The metallic outer portion or channel 22 ofthe end effector 12 or the metallic anvil 24 may serve as thecounter-electrode (or cathode) for each of the three upper activeelectrodes (or anodes) 500. The upper electrodes 500 may be coupled tothe RF source. When energized, RF energy may propagate between the upperelectrodes 500 and the counter electrode, coagulating tissue clampedbetween the electrodes.

The electrodes 500 may be energized simultaneously or in various orders,such as sequentially. For embodiments where the electrodes 500 areenergized according to a sequence, the sequence may be automatic(controlled, for example, by a controller (not shown) in communicationwith the RF source) or by selection by the user. For example, theproximate electrodes 500 ₃ could be energized first; then the middleelectrodes 500 ₂; then the distal electrodes 500 ₁. That way, theoperator (e.g., the operating surgeon) can selectively coagulate areasof the staple line. The electrodes in such an embodiment could becontrolled by a multiplexer and/or a multiple output generator, asdescribed further below. That way, the tissue under each electrode 500could be treated individually according to the coagulation needs. Eachelectrode in the pair may be connected to the RF source so that they areenergized at the same time. That is, for the distal pair of activeelectrodes 500 ₁, each, being on opposite sides of the knife channel,may be energized by the RF source at the same time. Same for the middlepair of electrodes 500 ₂ and the proximate pair of electrodes 500 ₃,although, in an embodiment where the electrode pairs are energized insequence, the distal pair is not energized at the same time as themiddle and proximate pairs, and so on.

Further, various electrical parameters, such as impedance, deliveredpower or energy, etc., could be monitored and the output to particularelectrodes 500 could be modified to produce the most desirable tissueeffect. Additionally, another advantage is in the case of a metal stapleor other electrically conductive object left from a previous instrumentfiring or surgical procedure that may cause a short of the electrodes.Such a short situation could be detected by the generator and/ormultiplexer, and the energy could be modulated in a manner appropriatefor the short circuit.

In addition, energizing the electrodes 500 in sequence reduces theinstantaneous power required from the RF source in comparison to adesign that would has one set of electrodes as long as the combinedlength of the three segmented electrodes 500 shown in FIG. 23. Forexample, for electrode configurations as shown in the '312 Patent, ithas been demonstrated that it would require fifty to one-hundred wattsto coagulate successfully forty-five mm lines on either side of the cutline. By using smaller active electrodes (e.g., the upper electrodes500) that have less surface area than the larger return electrodes(e.g., the metallic anvil 24), the smaller active electrodes 500 canconcentrate the therapeutic energy at the tissue while the larger,return electrode is used to complete the circuit with minimal impact onthe tissue interface. In addition, the return electrode preferably hasgreater mass and thereby is able to stay cooler during electrosurgicalapplication.

The electrodes 500 may be surrounded by an electrically insulatingmaterial 504, which may comprise a ceramic material.

FIG. 24 shows another embodiment having segmented RF electrodes. In theembodiment shown in FIG. 24, there are four co-linear segmentedelectrodes 500 ₁₋₄ of equal length (15 mm in this example). Like theembodiment of FIG. 23, the electrodes 500 of FIG. 24 could be energizedsimultaneously or sequentially.

FIG. 25 shows yet another embodiment, in which the segmented electrodeshave different lengths. In the illustrated embodiment, there are fourco-linear segmented electrodes, but the most distal electrodes 500 ₁,500 ₂ are 10 mm in length, and the two proximate electrodes 500 ₃, 500 ₄are 20 mm in length. Having short distal electrodes may provide theadvantage of concentrating the therapeutic energy, as mentioned above.

FIG. 59 shows an embodiment having fifteen pairs of segmented RFelectrodes 500 on a circuit board 570, or other type of suitablesubstrate, on the lower surface of the anvil 24 (i.e., the surfacefacing the channel 22). The various electrode pairs are energized by theRF source (or generator) 574. The multiplexer 576 may distribute the RFenergy to the various electrode pairs as desired under the control of acontroller 578. According to various embodiments, the RF source 574, themultiplexer 576, and the controller 578 may be located in the handle 6of the instrument.

In such an embodiment, the circuit board 570 may comprise multiplelayers that provide electrical connections between the multiplexer 576and the various electrode pairs. For example, as shown in FIGS. 60 to63, the circuit board may comprise three layers 580 ₁₋₃, each layer 580providing connections to five of the electrode pairs. For example, theupper most layer 580 ₃ may provide connections to the most proximatefive electrode pairs, as shown in FIGS. 60 and 61; the middle layer 580₂ may provide connections to the middle five electrode pairs, as shownin FIGS. 60 and 62; and the lowest layer 580 ₁ may provide connectionsto the most distal five electrode pairs, as shown in FIGS. 60 and 63.

FIG. 64 shows a cross-sectional end view of the anvil 24 according tosuch an embodiment. The circuit board 570, adjacent to the staplepockets 584, comprises three conducting layers 580 ₁₋₃, havinginsulating layers 582 ₁₋₄ therebetween. FIGS. 65 and 66 show how thevarious layers 580 ₁₋₃ may be stacked to connect back to the multiplexer576 in the handle.

An advantage of having so many RF electrodes in the end effector 12, asshown in FIG. 67, is that, in the case of a metal staple line 590 orother electrically conductive object left in the tissue 592 from aprevious instrument firing or surgical procedure that may cause a shortof the electrodes, such a short situation could be detected by thegenerator and multiplexer, and the energy could be modulated in a mannerappropriate for the short circuit.

FIG. 27 shows another end effector 12 with RF electrodes. In thisembodiment, the end effector 12 only comprises distal electrodes 500 ₁,with the metallic anvil 24 serving as the return electrode. The distalelectrodes 500 ₁ do not span the entire length of the anvil 24, but onlya fraction of the length. In the illustrated embodiment, distalelectrodes 500 ₁ are only approximately 20 mm in length along a 60 mmanvil, so that the distal electrodes 500 ₁ only cover approximately themost distal ⅓ of the anvil length. In other embodiments, the distalelectrodes 500 ₁ could cover the most distal 1/10 to ½ of the anvillength. Such embodiments could be used for spot coagulation, asdescribed in U.S. Pat. No. 5,599,350, which is incorporated herein byreference.

FIG. 28 shows yet another embodiment of the end effector 12 with RFelectrodes. In this embodiment, an active electrode 500 is positioned atthe distal tip of the anvil 24, insulated by the anvil 24 by anelectrically non-conductive insulator 504, which may be made of ceramicmaterial. Such an embodiment may be used for spot coagulation.

FIGS. 29 to 32 illustrate other embodiments of the end effector 12 thatmay be useful for spot coagulation. In these embodiments, the anvil 24comprises a pair of electrodes 500 ₁, 500 ₂ at the distal end of theanvil 24 and along a lateral side of the anvil 24. FIG. 29 is front-endview of the anvil 24 according to such an embodiment, FIG. 30 is a sideview, FIG. 31 is an enlarged fragmentary front-end view, and FIG. 32 isa top view. In such an embodiment, the metallic anvil 24 may act as thereturn electrode. The active electrodes 500 ₁, 500 ₂ may be insulatedfrom the anvil 24 by electrically non-conductive insulators 504, whichmay comprise ceramic material.

FIGS. 33 to 36 show an embodiment where the anvil 24 comprises twodistal electrodes 500 ₁, 500 ₂ located at the top, center of the anvil24. Again, the metallic anvil 24 may act as the return electrode, andthe active electrodes 500 ₁, 500 ₂ may be insulated from the anvil 24 byelectrically non-conductive insulators 504.

FIGS. 37 to 40 show an embodiment where one active electrode 500 ₁(e.g., the active electrode) is positioned on the anvil 24, and anotheractive electrode 500 ₂ is positioned on the lower jaw 22, and preferablyon the cartridge 34. The metallic anvil 24 may serve as the returnelectrode. The anvil electrode 500 ₁ is insulated from the anvil 24 byan insulator 504. The electrode 500 ₂, being positioned in the cartridge34, which is preferably made from a non-conductive material such asplastic, is insulated from the metallic channel 22 by the cartridge 34.

FIGS. 41 to 44 show an embodiment where the anvil 24 has two activeelectrodes 500 ₁, 500 ₂ at the very most distal end of the anvil 24 thatextend completely from the upper surface of the anvil 24 to the lowersurface. Again, the metallic anvil 24 may act as the return electrode,and the active electrodes 500 ₁, 500 ₂ may be insulated from the anvil24 by electrically non-conductive insulators 504.

FIGS. 45 to 48 show an embodiment where the cartridge 34 has two activeelectrodes 500 ₁, 500 ₂ at the very most distal end of the staplecartridge 34. In such an embodiment, the metallic anvil 24 or themetallic channel 22 may act as the return electrode. In this illustratedembodiment, the electrodes 500 ₁, 500 ₂ are connected to insulatorinserts 503, but in other embodiments, the insulator inserts 503 couldbe omitted and the plastic cartridge 34 may serve as the insulator forthe electrodes 500 ₁, 500 ₂.

FIGS. 49 to 52 show an embodiment having one active electrode 500 ₁ atthe very most distal end of the anvil 24 and another active electrode500 ₂ at the very most distal end of the cartridge 34. Again, in such anembodiment, the metallic anvil 24 or the metallic channel 22 may act asthe return electrode. In this illustrated embodiment, the electrode 500₂ is connected to insulator inserts 503, 505, but in other embodiments,the insulator inserts 503, 505 could be omitted and the plasticcartridge 34 may serve as the insulator for the electrode 500 ₂.

FIG. 57 is a side view and FIG. 58 is a cross-sectional side of thehandle 6 according to other embodiments of the present invention. Theillustrated embodiment only includes one trigger, the closure trigger18. Activation of the knife, staple drivers, and/or RF electrodes inthis embodiment may be achieved through means other than a separatefiring trigger. For example, as shown in FIG. 57, actuation of theknife, staple drivers, and/or RF electrodes may be activated by apush-button switch 540 or other type of switch that is in a positionthat is convenient for the operator. In FIG. 57, the switch 540 is shownat the most proximate portion of the handle 6. In another embodiment,the switch may be positioned near the distal end of the handle 6 so thatpulling of the nozzle 539 activates the switch to cause actuation of theinstrument. In such an embodiment, a switch (not shown) may be placedunder or near the nozzle 539 so that movement of the nozzles toggles theswitch.

Alternatively, actuation of the knife, staple drivers, and/or RFelectrodes may be activated by voice or other sound commands detected bya microphone 542. In other embodiments, the handle 6 may comprise a RFor sonic transceiver 541, which may receive and/or transmit RF or sonicsignals to activate the instrument. Also, as shown in FIG. 58, a footpedal or switch 544 could be used to active the instrument 10. The footpedal 544 may be connected to the handle 6 by a cord 545. Also, thehandle 6 may comprise a dial control 546 or some other suitable controldevice for controlling actuation of the segmented RF electrodes (see,for example, FIGS. 23 and 24). Using such a control device 546, theoperator may serially activate the various pairs of RF electrodes 500 inthe end effector 12.

The instrument 10 shown in FIGS. 57 and 58 also includes many feedbacksystems for the user. As mentioned above, the instrument 10 may comprisethe speaker 543 for audibleizing commands or instructions to theoperator. In addition, the handle 6 may comprise visual indicators 548,such as LEDs or other light sources that provide visual feedbackregarding actuation of the various segmented RF electrodes. For example,each of the visual indicators 548 could correspond to one of thesegmented RF electrode pairs. The corresponding visual indicator 548 maybe activated when the segmented RF electrode pair is activated. Inaddition, the handle 6 may comprise an alphanumeric display 550, whichmay be an LED or LCD display, for example. The display 550 may beconnected to a circuit board 552 inside the handle 6. The handle 6 mayalso comprise a vibrator 554 in the pistol grip portion 26 that mayprovide vibrational feedback to the operator. For example, the vibrator554 could vibrate each time that one of the segmented pairs of the RFelectrodes in the end effector 12 is activated.

FIG. 26 is a cross-sectional view of the end effector 12 according tovarious embodiments where the electrodes are on the upper jaw (or anvil)24. In the illustrated embodiment, the active electrodes 500 arepositioned adjacent the knife slot 516. The metal anvil 24 may serve asthe return electrode. Insulators 504, which may be made of ceramic,insulate the electrodes 500 from the metallic anvil 24. The embodimentof FIG. 68 is similar to that of FIG. 26, except that electrodes 500 aremade smaller, such that a portion of the insulators 504 can extendbetween the respective electrodes 500 and the edges of the knife channel516.

FIG. 53 is a cross-sectional end view of the end effector 12 accordingto another embodiment. In this embodiment, like the embodiment of FIG.26, the active electrodes 500 ₁, 500 ₂ are on the anvil 24 on oppositesides of the knife channel. The electrodes 500 ₁, 500 ₂ are insulatedfrom the metallic anvil by insulators 504, which again preferablycomprise ceramic material. In this embodiment, however, the insulators504 are made very thin (compare with FIG. 26). Making the insulators 504very thin provides the potential advantage that the anvil 24 may includea relatively large metal section 520 above the electrodes 500, therebypotentially supporting a slimmer anvil profile for a given anvilstiffness, or a stiffer profile for a given anvil cross-sectionaldimension. The insulators 504 may be cast in or sputter coated onto theanvil 24.

FIG. 54 illustrates another embodiment. In this embodiment, the activeelectrodes 500 ₁, 500 ₂ are sputter coated or bonded to the insulators504, which may also be sputter coated or bonded to the anvil 24. Likethe embodiment of FIG. 53, this design allows for more anvil materialabove the electrodes. In such an embodiment, the electrodes 500 ₁, 500 ₂may comprise silver, which is a good conductor of electricity and hasantimicrobial properties.

FIG. 55 shows a side view of the end effector according to anotherembodiment. In this embodiment, a thin film of electrically insulatingmaterial 530 is deposited on the face of the cartridge 34. Theinsulating film 530 preferably comprises a heat- and arc-resistantmaterial, such as ceramic. This would tend to increase the resistance ofthe cartridge 34 to arc-tracking and shorting, permitting more firingsbetween changes of the cartridge 34. In addition, if the cartridge 34was a poor electrical conductor, it would support quicker heating oftissue and reduce the overall energy requirements. The active electrodes(not shown in FIG. 55) may be in the anvil 24, as described inembodiments above.

FIG. 56 shows an embodiment that is similar to that shown in FIG. 55,except that in FIG. 56, a thin layer 532 of slightly electricallyconductive material is deposited on top of the insulating film 530. Theconductivity of the thin, slightly conductive layer 532 may be lowerthan the conductive of the tissue clamped in the end effector 12 fortreatment. As such, the thin, slightly conductive layer 532 wouldprovide a reduced-conductivity path to provide additional heating of theclamped tissue. This would tend to reduce the time required to heat thetissue and achieve coagulation.

As described above, the instrument 10 may comprise an articulation pivot14 for articulating the end effector 12. A clinician or operator of theinstrument 10 may articulate the end effector 12 relative to the shaft 8by utilizing the articulation control 16, as described in more detail inpublished U.S. Patent Application Publication No. 2007/0158385, entitledSURGICAL INSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat.No. 7,670,334, which is incorporated herein by reference. In otherembodiments, rather than a control device that is integrated with theinstrument 10, the end effector 12 may be articulated by a separateinstrument, such as gripper, that is inserted into the patient so thatits operative portion is near the end effector 12 so that it canarticulate the end effector 12 as desired. The separate instrument maybe inserted through a different opening as the end effector 12, orthrough the same opening. Also, different operators can operate theseparate instruments, or one person can operate both instruments, toarticulate the end effector 12. In another passive articulationscenario, the end effector 12 may be articulated by carefully pushing itagainst other parts of the patient to achieve the desired articulation.

In another embodiment, the end effector 12 may be connected to thehandle by a flexible cable. In such an embodiment, the end effector 12could be positioned as desired and held in position by use of anotherinstrument, e.g., a separate gripper instrument. In addition, in otherembodiments, the end effector 12 could be positioned by a separateinstrument and clamped by a second separate instrument. In addition, theend effector 12 could be made sufficiently small, such as 8 to 9 mm wideby 10 to 11 mm tall, so that a pull-to-close mechanism could be used toclamp the end effector from the handle 6. The pull-to-close mechanismcould be adapted from that described in U.S. Pat. No. 5,562,701,entitled CABLE-ACTUATED JAW ASSEMBLY FOR SURGICAL INSTRUMENTS, which isincorporated herein by reference. The cable 600 could be disposed in oralong a flexible endoscope for use, for example, in upper or lowergastro-intestinal tract procedures.

In yet another embodiment, as shown in FIGS. 69 and 70, the instrument10 may comprise a flexible neck assembly 732 enabling articulation ofthe end effector 12. When an articulation transmission assembly 731coupled to the shaft 8 is rotated, it may cause remote articulation ofthe flexible neck assembly 732. The flexible neck assembly 732 maycomprise first and second flexible neck portions 733, 734, which receivefirst and second flexible band assemblies 735, 736. Upon rotation of thearticulation transmission assembly 731, one of the first and secondflexible transmission band assemblies 735, 736 is moved forwardly andthe other band assembly is moved rearwardly. In response to thereciprocating movement of the band assemblies within the first andsecond flexible neck portions 733, 734 of the flexible neck assembly732, the flexible neck assembly 732 bends to provide articulation. Afurther description of the flexible neck is described in U.S. Pat. No.5,704,534, which is incorporated herein by reference.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Preferably, the various embodiments of the invention described hereinwill be processed before surgery. First, a new or used instrument isobtained and if necessary cleaned. The instrument can then besterilized. In one sterilization technique, the instrument is placed ina closed and sealed container, such as a thermoformed plastic shellcovered with a sheet of TYVEK (commercially available from E. I. du Pontde Nemours and Company). The container and instrument are then placed ina field of radiation that can penetrate the container, such as gammaradiation, x-rays, or high-energy electrons. The radiation killsbacteria on the instrument and in the container. The sterilizedinstrument can then be stored in the sterile container. The sealedcontainer keeps the instrument sterile until it is opened in the medicalfacility.

It is preferred that the device is sterilized. This can be done by anynumber of ways known to those skilled in the art including beta or gammaradiation, ethylene oxide, steam and other methods.

While the present invention has been illustrated by description ofseveral embodiments and while the illustrative embodiments have beendescribed in considerable detail, it is not the intention of theapplicant to restrict or in any way limit the scope of the appendedclaims to such detail. Additional advantages and modifications mayreadily appear to those skilled in the art. The various embodiments ofthe present invention represent vast improvements over prior staplemethods that require the use of different sizes of staples in a singlecartridge to achieve staples that have differing formed (final) heights.

Accordingly, the present invention has been discussed in terms ofendoscopic procedures and apparatus. However, use herein of terms suchas “endoscopic” should not be construed to limit the present inventionto a surgical stapling and severing instrument for use only inconjunction with an endoscopic tube (i.e., trocar). On the contrary, itis believed that the present invention may find use in any procedurewhere access is limited, including but not limited to laparoscopicprocedures, as well as open procedures. Moreover, the unique and novelaspects of the various staple cartridge embodiments of the presentinvention may find utility when used in connection with other forms ofstapling apparatuses without departing from the spirit and scope of thepresent invention.

What is claimed is:
 1. A surgical instrument, comprising: a first jaw; asecond jaw, wherein the first jaw is movable relative to the second jawto capture tissue between the first jaw and the second jaw; a staplecartridge supported by the second jaw, wherein the staple cartridgecomprises staples removably stored therein; a firing system configuredto drive the staples toward the first jaw; an electric motormechanically coupled to the firing system; a power source electricallycouplable to the electric motor; and a control system electricallyconnected to the power source, wherein the control system is configuredto: determine a first level of power supplied by the power source; andapply a second level of power to the electric motor if the first levelof power exceeds a predetermined threshold, wherein the second level ofpower is lower than the first level of power.
 2. The surgical instrumentof claim 1, wherein the first jaw comprises an anvil.
 3. The surgicalinstrument of claim 1, wherein the staple cartridge is removably seatedin the second jaw.
 4. The surgical instrument of claim 1, wherein thepower source comprises a rechargeable power source.
 5. The surgicalinstrument of claim 1, wherein the power source comprises a replaceablepower source.
 6. The surgical instrument of claim 1, wherein the powersource comprises a plurality of battery cells.
 7. The surgicalinstrument of claim 1, wherein the control system comprises a powerregulator electrically connected to the power source and the electricmotor.
 8. The surgical instrument of claim 7, wherein the powerregulator is configured to control a voltage applied to the electricmotor.
 9. The surgical instrument of claim 1, wherein the control systemis further configured to measure: a power source voltage; and a currentdrawn from the power source.
 10. A surgical instrument, comprising: anelongate channel; an anvil pivotably coupled to the elongate channel; astaple cartridge positioned within the elongate channel; staplesremovably positioned within the staple cartridge; a firing systemconfigured to fire the staples toward the anvil; an electric motormechanically coupled to the firing system; a power source electricallycouplable to the electric motor; a power regulator electrically coupledto the power source and the electric motor, wherein a setpoint of thepower regulator is adjustable; and a control system configured to lowerthe setpoint of the power regulator if a level of power supplied by thepower source exceeds a predetermined threshold.
 11. The surgicalinstrument of claim 10, wherein the staple cartridge is a replaceablestaple cartridge.
 12. The surgical instrument of claim 10, wherein thepower source comprises a rechargeable power source.
 13. The surgicalinstrument of claim 10, wherein the power source comprises a replaceablepower source.
 14. The surgical instrument of claim 10, wherein the powersource comprises a plurality of battery cells.
 15. The surgicalinstrument of claim 10, wherein the control system is further configuredto measure: a power source voltage; and a current drawn from the powersource.
 16. A surgical instrument, comprising: a first jaw; a second jawpivotably connected to the first jaw; a replaceable staple cartridgeremovably positioned within the second jaw; staples removably positionedwithin the replaceable staple cartridge; a firing system configured tofire the staples toward the first jaw; an electric motor mechanicallycoupled to the firing system; a power source electrically couplable tothe electric motor; and means for reducing a voltage applied to theelectric motor if a level of power supplied by the power source exceedsa predetermined threshold.